如何处理实体框架中的主键5代码首先 [英] How to Handle Primary Key in Entity Framework 5 Code First

问题描述

在我的EF5代码优先模型中，如果数据库设置主键，创建新记录的效果会更好。我正在使用Guid的主键，如果设置了 DatabaseGeneratedOption.Identity ，SQL Server将始终创建 uniqueidentifier 。

但是，当我尝试初始种子数据库时，会导致问题。如果我在我的种子方法中设置Guid，SQL Server会覆盖它。如果我没有设定Guid，我每次都会获得新的记录。什么是建议的解决方案来种子数据库使用预设的Guid和保持 DatabaseGeneratedOption.Identity 设置为我的正常操作？

示例类模型：

  [Key] 
 [DatabaseGenerated（DatabaseGeneratedOption.Identity）] 
 public Guid Id {get;组; } 
 public RecordName {get;组; } 
 public DateTime？创建{get;组; } 
 public DateTime？更新{get;组; 
  

种子方法示例：

  var record = new Record（）
 {
 Id = new Guid（3B80725E-9550-4933-807F-C2FAA0942225），
 RecordName =New记录，
 Created = DateTime.UtcNow，
更新= DateTime.UtcNow，
}; 
 context.Record.AddOrUpdate（record）; 
 context.SaveChanges（）; 
  

解决方案

AddOrUpdate有一个覆盖，允许您指定密钥

从 MSDN

所以你需要提供自然键的方法：

  context.Record.AddOrUpdate（c => c.RecordName，new Record（）
 {
 RecordName =New Record，
 Created = DateTime.UtcNow， 
更新= DateTime.UtcNow，
}）
  

In my EF5 code-first models, creation of new records works better if the database sets the primary key. I am using a Guid for primary key and if DatabaseGeneratedOption.Identity is set, SQL Server will always create the uniqueidentifier.

However, this causes issues when I am trying to initially seed the database. If I set the Guid in my seed method, SQL Server overrides it. If I don't set the Guid, I get a new record every time. What is a recommended solution to seed the database using pre-set Guids and keep DatabaseGeneratedOption.Identity set for my normal operations?

Example class model:

[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid Id { get; set; }
public RecordName { get; set; }
public DateTime? Created { get; set; }
public DateTime? Updated { get; set; }

Example seed method:

var record = new Record()
            {
                Id = new Guid("3B80725E-9550-4933-807F-C2FAA0942225"),
                RecordName = "New Record",
                Created = DateTime.UtcNow,
                Updated = DateTime.UtcNow,
             };
context.Record.AddOrUpdate(record);
context.SaveChanges();

解决方案

AddOrUpdate has an override that allows you to specify the key

From MSDN

So you need to supply the method with the natural key:

context.Record.AddOrUpdate(c => c.RecordName, new Record()
            {
                RecordName = "New Record",
                Created = DateTime.UtcNow,
                Updated = DateTime.UtcNow,
             })

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